Learned a new term today: incestuous amplification

Back during the early days of the Iraq debacle, I learned that the military has a term for how highly dubious ideas become not just accepted, but viewed as certainties. “Incestuous amplification” happen when a closed group of people repeat the same things to each other – and when accepting the group’s preconceptions itself becomes a necessary ticket to being in the in-group. A fundamentally flawed notion – say, that the Germans can’t possibly attack though the Ardennes – becomes part of what everyone knows, where “everyone” means by definition only people who accept the flawed notion.